Resilient Routing for the Control-Channel of Software-Defined Networks – A Revisit of a JSAC Article

Perspectives

• Writing this article was a great pleasure because the proposed algorithm provides optimal routing protection for control-plane traffic in the in-band fashioned software-defined networks. Importantly, the proposed approach can be extended to the general routing protection in the data plane of Software-define Networks.
  

What is it about?

• In the software-defined heterogeneous networks, we study a weighted cost minimization problem, in which the control-plane traffic load balancing and control-channel setup cost are jointly considered when selecting the protection paths for control channels. Since the multiple resource-constrained routing is proved to be NP-complete, we propose a near-optimal algorithm, using the Markov approximation technique. Particularly, we extend our solution to an online case that can handle dynamic single-link failures. The incurred performance fluctuation is also theoretically analyzed.
  

Why is it important?

• Even though SDN brings quantities of advantages to the software-defined heterogeneous network (HetNet), it comes with many challenges. One particular concern is the resilience of the control traffic, i.e., the communications between data-plane and control-plane. In an in-band fashioned software-defined heterogeneous network, where control-plane traffic shares medium with the data plane traffic, even a single link failure may disconnect a large number of packet-switching devices from their controllers, resulting in much worse damages than those of the out-of-band fashion. For example, in case of failures caused by disaster scenarios such as earthquake and tsunami, the core network links between switches and controllers may be disconnected. That would result in severe performance degradation, including packet loss, loop routing, suboptimal or infeasible routing actions, high network latency, and even service unavailability. The consequence becomes even worse in wide-area software-defined HetNets. Therefore, to deal with routing protection at the control plane for in-band HetNets is a fundamental issue.

=============== Chinese Version ================

为软件定义网络的控制信道提供可靠的路由策略 – 回顾一篇发表在JSAC的代表作

这篇blog介绍我之前的一篇发表在JSAC的技术论文，论文信息如下：

Huawei Huang, Song Guo, Weifa Liang, Keqiu Li, Baoliu Ye, and Weihua Zhuang, “Near-Optimal Routing Protection for In-Band Software-Defined Heterogeneous Networks”, IEEE Journal on Selected Areas in Communications (JSAC), vol. 16, no. 20, pp. 7421-7432, November 2016.(CCF-A类, 计算机网络)

观点 [Perspectives]

• 很高兴看到这篇组成我博士毕业论文三分之一分量的论文，可以为软件定义网络的控制信道提供可靠的路由保护策略。

论文亮点 [What is it about?]

• 我们在此文针对软件定义网络的异构网络，研究一个既考虑到铺设控制信道代价，又考虑到控制信道由于链路失效的弹性恢复的可靠性的联合优化问题。为了解决这个NP-complete的难题，我们提出采用基于Markov approximation技术设计一个接近最优性能的算法。此算法可以实时有效地处理单链路失效。而且，我们还针对算法的动荡性给出了理论证明分析。

为何这个课题重要 [Why is it important?]

• 在基于软件定义网络的异构网络，如5G边缘社区网络，为控制信道提供可靠的路由保护策略至关重要，因为控制信道是服务流量的背后控制通道。特别是以“in-band”, 即“带内”方式组建的SDN控制信道，服务流量与控制流量“穿行”在同样的网络链路上。所以，一个简单的单链路失效事件就会使得很大一部分控制流与服务流丢包，从而对用户的服务体验造成灾难性的后果。为此，如何为软件定义网络的控制信道提供高可靠、具有快速恢复能力的路由保护策略是一个至关重要的研究课题。